Merge pull request #1245 from akshaymagar2003/main

Heap Sort implemented in C++

Author: akgmage

sorting/heapSort.cpp

@@ -0,0 +1,66 @@
+/*This implementation uses a vector<int> to store the elements to be sorted. The heapify function is used to create a max heap and maintain the heap property. The heapSort function performs the heap sort algorithm by repeatedly extracting the maximum element from the heap. Finally, the printArray function is a utility function to print the elements of an array.*/
+/* time complexity O(n log n)
+   Space  complexity  O(1) */
+#include <iostream>
+#include <vector>
+
+using namespace std;
+
+void heapify(vector<int>& arr, int n, int i) {
+    int largest = i; // Initialize largest as root
+    int left = 2 * i + 1; // Left child
+    int right = 2 * i + 2; // Right child
+
+    // If left child is larger than root
+    if (left < n && arr[left] > arr[largest])
+        largest = left;
+
+    // If right child is larger than largest so far
+    if (right < n && arr[right] > arr[largest])
+        largest = right;
+
+    // If largest is not root
+    if (largest != i) {
+        swap(arr[i], arr[largest]);
+
+        // Recursively heapify the affected sub-tree
+        heapify(arr, n, largest);
+    }
+}
+
+void heapSort(vector<int>& arr) {
+    int n = arr.size();
+
+    // Build heap (rearrange array)
+    for (int i = n / 2 - 1; i >= 0; i--)
+        heapify(arr, n, i);
+
+    // One by one extract an element from heap
+    for (int i = n - 1; i > 0; i--) {
+        // Move current root to end
+        swap(arr[0], arr[i]);
+
+        // call max heapify on the reduced heap
+        heapify(arr, i, 0);
+    }
+}
+
+// Utility function to print an array
+void printArray(const vector<int>& arr) {
+    for (int i = 0; i < arr.size(); ++i)
+        cout << arr[i] << " ";
+    cout << endl;
+}
+
+int main() {
+    vector<int> arr = {12, 11, 13, 5, 6, 7};
+    cout << "Original array: ";
+    printArray(arr);
+
+    heapSort(arr);
+
+    cout << "Sorted array: ";
+    printArray(arr);
+
+    return 0;
+}